Power-operated curb cover for centrifugal machines



Jan. 20, 1959 J. HERTRICH 7 2,859,726

POWER-OPERATED CURB COVER FOR CENTRIFUGAL MACHINES Filed July 6, 1954 s Sheets-Sheet 1 I N V E NTO R Josy/E H's/721th, tlec eased BY [/zseber rye/i,

TTORNEYS Jan. 20, 1959 JQHERTRQICH 2,8

POWER-OPERATED CURB COVER FOR CENTRIFUGAL MACHINES Filed July 6, 1954 s Sheets-Sheet 2 NVENTOR J0 5e fled/126, deceased Jan. 20, 1959 J. HERTRICH 2,369,726

POWER-OPERATED CURB COVER FOR CENTRIFUGAL MACHINES Filed July 6, 1954 3 Sheets-Sheet s I l i United States Patent POWER-OPERATED CURB COVER FOR CENTRIFUGAL MACHINES Joseph Hertrich, deceased, late of Hamilton, Ohio, by Elise Hertrich, executrix, Hamilton, Ohio, assignor to The Western States Machine Company, Hamilton, Ohio, a corporation of Utah Application July 6, 1954, Serial No. 441,369

8 Claims. (Cl. 210-142) This invention relates to improvements in centrifugal apparatus of the type employed in the manufacture and refining of sugar and, more particularly, to new centrifugal cnrb top covers and new combinations thereof with power-operated driving mechanisms and with loading control mechanisms.

In the manufacturing and refining of sugar in the usual open top centrifugal, a supply tank, or centrifugal mixer, is provided adjacent the centrifugal to hold a comparatively large quantity of sugar massecuite or magma to be purged. Such tanks have a loading spout extending therefrom to gate-controlled outlets from which charge material can flow from the tank into the centrifugal. Such centrifugals are usually provided with a curb having a top opening that is normally closed by a movable cover so as to exclude foreign matter and the outside atmosphere from the environs of the centrifugal basket when a charge is being processed. At the time of each loading operation, the curb top cover is opened before the loading gate on the supply tank spout is opened, and it is closed after the loading gate has been closed. In addition, a charge-guiding drip pan is usually provided for directing the material flowing from the tank into the centrifugal basket when the loading gate is opened and for catching drippings from the loading gate when the latter is closed. This drip pan is generally scraped by the attendant at the completion of each loading operation to deposit the collected drippings into the basket.

Although automatic controls have been provided for governing the operation of loading gates which serve sugar centrifugals, the laborious and time consuming steps of opening and closing the curb cover and scraping the drip pan are still performed manually for lack of a reliable and eflicient means of performing them otherwise.

One of the objects of this invention is to provide an improved organization of a centrifugal machine having an automatic cycle control including a sliding curb cover that is controlled automatically at the time of each loading operation yet can be opened and closed as desired under manual control at any time either in or out of the automatic cycle.

A further object is to provide such an organization having control means that prevent in a positive manner opening of the loading gate in the automatic cycle when the curb cover is closed but permit free movement of the curb cover to and from open position under the desired manual control of the centrifugal operator without interfering with the normal cyclical operation of the loading gate operating mechanism.

Another object of this invention is to provide for sugar centrifugals an improved curb cover construction which can be used in conjunction with automatic control mechanisms for the provision of a completely automatic cyclical sugar centrifugal.

According to an important feature of this'invention, a curb cover element is mounted on a curb top for swinging movement over otherwise unused portions of the curb top froma normal closed position covering the curb 2,869,726 Patented Jan. 20, 1959 ICC top opening to an open position exposing the opening by a pair of links that are each pivotally secured to the cover at one end and swiveled on the curb top at the other end. The links are so arranged that. displacement of the cover to and from open position is effected by movement of the cover through a relatively small arcuate path throughout which the cover remains parallel to its closed position.

According to another feature of this invention, movement of the cover to open position is effected by poweroperated means or by manually operable means that can be operated independently of the power-operated means. Movement of the cover to closed position is efiected by yieldable means that are arranged to act .continuously to urge the cover to closed position with a limited force that is overbalanced by the force of the power-operated means, or by a force applied manually by the centrifugal attendant, which moves the cover to open position. Thus, inactivation of the power-operated means or release of the manually operated means results in movement of the cover to closed position by the yieldable means.

The power-operated means employed in the new arrangment is preferably a fluid pressure operated motor that is combined with adjustable control means that regulate the rate of flow of fluid to and from the fluid pressure operated motor so that the respective movement of the cover to and from open position may be effected at predetermined rates.

The invention further provides control means for the loading gate opening motor, together with acutating means for such control means which respond to movements of the cover for moving the control means to a position in which the gate opening means are rendered inoperable when the cover is closed and to a position in which the gate opening means are rendered operable when the cover is opened. In this way the loading gatecannot be opened until the curb top cover has been so. moved away from its closed position that the path of flow of charge material from the supply tank to the centrifugal basket is not obstructed. This assures an efficient and thoroughly reliable automatic loading operation, for it mechanically determines the proper time at which the loading operation should begin and it avoids the detrimental eifects that might otherwise result if the automatic controls effected opening of the gate in a cycle in which the cover failed to open.

Another featureof the invention lies in the improved curb cover construction whereby the movable curb cover element is provided with an integrally formed trough that serves to catch drippings that fall from the loading gate when the cover is closed and to continuously dispose of such drippings by draining them into a receptacle that underlies an outlet in the trough throughout the path of its movement with the trough and cover. With a curb cover of this character, the trough is displaced from below the loading gate when the cover element is moved to its open position and the loading gate is advantageously positioned directly over the curb top opening so that charge material flowing from the gate in each loading operation falls directly into the basket and doesnot require the use of the usual charge-guiding drip pan. And the continuous disposal of the drippings that fall into the trough eliminates the loss of time and physical burden involved in scraping out a conventional drip pan at the end of each loading operation. The elimination of the scraping operation renders the improved cover arrangement especially suitable for automatic cyclical operation.

Other objects, features and advantages of this invention will become apparent from the following detailed description. and the accompanying drawings showing. an. illustrative embodiment of the invention.

In the drawings:

Figure 1 is; a plan view of'a centrifugal curb top provide-diwith an improved sliding cover. element in accordance' with. my invention, the cover element being shown in closed position;

Figure 2 is. a plan, view similar to Figure 1, with the curb' top cover element in open position;

Figure. 3 is a fragmentary side elevation of the centrifugal curb and the curb top cover element, the curb being partially broken away to show the drippings receiver within the curb. The phantom lines in this figure indicate the position of the usual loading chute and control gate overlying the curb;

Figure 4 is a vertical transverse section through the drippings catching trough formed on the sliding cover element, taken on lines 44 of Figure 2;

Figure 5' is a diagrammatic view of a flow circuit and of motor and control! elements for controlling operation of'themovable curb top cover element, together with means for rendering the loading gate inoperable when the curb cover'is in closed position; and

Figure 6 is a diagrammatic longitudinal cross-section through part of the control mechanism of Figure 5-.

The drawings show a form of curb top cover provided in accordance with this invention in operative association with the curb top of a suspended centrifugal and a loading gate. The curb 10 surrounds a perforate cen- .trifugal basket 12, which is suspended on a vertical spindle 14 and adapted to be revolved at high speed to effect separation of liquid and solid materials introduced' into the basket. The curb has a top Wall 16 with a central opening 18' therein permitting access to the basket. Sugar massecuite or magma is delivered for centrifugal treatment from a mixer tank (not shown) through a loading spout 22 and thence into the basket when a loading gate 20 of any suitable'construction is moved' away from its position closing the spout outlet. Gate 20 is connected with the reciprocatory plunger 24 (see Figure 5) of a double acting air cylinder 26 which serves as a motor both for opening andclosing the loading gate. It will be evident that when the gate motor control device 26a is operated to pass air under suitable pressure into the lower part of cylinder 26 through conduit 28 and to vent conduit 30, the gate 20 will be lifted .to an open position in which charge material in the mixer tank will flow freely into basket 12'. When the gate motor control device 26a is actuated to pass air under pressure through line 30 to the upper part of cylinder 26 and to vent line 28;. the gate 26 will be moved downward to a closed. position.

7 All of this is well known in the art. It is also. wellknown to provide acover for normally closing the curb top opening so that objectionable air currents and foreign matter are prevented from entering the basket and having harmful effectson the contents of the basket. Such cover must be opened at the time of each loading operation. before opening of the. loading gate takes place to expose the curb top opening; and permit free access to the basket. so that a charge: may be introduced. into the basket.

In accordance with this invention, a new and improved curb top cover unit is provided that embodies several important new features of construction and operation. In.the preferred. form. shown in.the drawings, the cover unitv comprises amovable. cover element 34 that is adapted in. closed' position. to fit together. with a stationary cover element 32 and substantially cover the opening 18v in the curb top and isadapted to move freely to an open position exposing the opening. Stationary cover element 32 is fixed on the curb top by bolts 36.

The. movable cover element 34- is' pivotally mounted to swing horizontally to' and from closed position in: an

4 arcuate path on unused portions of the curb top with the cover element remaining parallel to its closed position throughout such movement. In the preferred form shown, the mounting means include a pair of links 38 and 40, which are swivelled at their one ends to an integral, backward extension 1600f the curb top by pivots 42 and 44 pivotally connected at their other ends to opposite sides of the movable cover element 34 at 46 and 48, respectively. The pivots 42, 44, 46 and 43 of links 33 and 4t) define substantially a parallelogram so that a line passing through movable pivots 46 and 48 on the movable cover element 34 remains parallel to a line passing through the fixed pivots 42 and 44 throughout the path of movement of such cover element. The opening and closing movements of the cover may be brought about either by manual means or by power-operated means.

The swinging movements of the cover to and from closed position under power-operated means are carried,

out and limited in the following manner. A single-act ing fluid pressure motor comprising an air cylinder 50 having a plunger 52 is supported in a horizontal'position between the links 38 and 40 by brackets- 54 and 56, which are secured at one end to the cylinder and plunger, respectively, and swivelled at the other ends to pivot 42 on the curb top and pivot 58 on link 48, respectively. The plunger carries a piston 52a within the cylinder and the stroke of the plunger 52 is fixed so that when the plunger lies at the inner limit of its movement in cylinder St), the cover will be disposed in closed position, as shown in Figure 1, while at the outer limit of plunger movement the cover will be held in open position, as shown in Figure 2. The cylinder has an air inlet 60 connected with an air conduit 62 through which air under pressure may beeither admitted into the cylinder for moving the cover to open position or expelled from the cylinder during closing movement of the cover.

It will be seen, therefore, that the admission of. air pressure into the cylinder 50 forces the piston 52a to the right as viewed in Figure l to move the plunger 52 outwardly and swing link 40 counterclockwise about pivot 44. As link 40 is so moved, the cover is moved to open position in a horizontal arcuate path with the cover being constrained to remain parallel to its closed position by the coordinating action of the link 38 which is simultaneously swung in a counterclockwise direction about pivot 42 in an arc corresponding to that through which link 40 moves.

0n the other hand, when the pressure in cylinder 50' is released by venting line 62, the piston 52a is free to slide to the left as viewed in. Figure 1. When this happens, the cover is swung back to its closed. position. by the action of a tension spring 66 uponlinks 38 and 40. The tension spring has its ends fixed to the links at unequal distances from the fixed pivot axes of the links; the connection 68 of the spring with link 38 is closer to the pivot 42 than the connection '70 of the. spring with link 4t) is to pivot 44. By this arrangement, when the cover is moved to open position, the counterclockwise movement of the links stresses the springv and causes it to exert a moment in a clockwise direction upon-link 40 that is greater than the counterclockwise moment exerted upon link 38. Thus, it will be seen that the spring continuously exerts a force urging the links to their original positions so that when the pressure in cylinder 50 is released, the links swingclockwise under the action of the. spring andv move the cover. to closed position.

For. admitting fluid pressure into the: cover motor cylinder 50, the air conduit 62 leads to a manually operable three-way valve 63 which is normally positioned, as shown in Figure 5, to connect conduit 62 through duct 144, T connection 146' andduct 1.48. to. asolenoid valve GSV that is movable-between. a normal positionv venting duct- 148; through port 152-. and. an. energized. position. con

therewith about pivot 44.

hecting'duct 148 with a header 150 that leads to a source of fluid under pressure. It results that actuation of the valve GSV to move it to its energized position, which may be brought about automatically at the desired time in the automatic cycle of operation of the centrifugal, and to admit compressed air into duct 62 through valve '63, duct 144, T 146 and duct 148, brings into cover motor chamber 50 fluid pressure which forces piston 52a and plunger 52 to the right as viewed in Figure l to effect opening of the cover element 34. In order to bring about closing of the cover, the solenoid valve GSV is deenergized to return it to its normal position in which conduit 62 is vented through valve 63, duct 144, T 146, duct 148 and port 152. It results that the force of the fluid pressure acting on piston 52a is released and the cover element 34 is free to slide back to its closed position under the action of tension spring 66 as described above.

Alternatively, the curb cover element 34 may be operated under selective manual remote control. To accomplish this, three-way manually operated valve 63, which may be located at any suitable location accessible to the centrifugal attendant, has a direct connection with a branch 158a of the header 150. It will be evident from Figure 5 that rotation of the valve 63 to disconnect air conduit 62 and duct 144 and to connect air conduit 62 and branch 150a of the header results in the admission of air under pressure into the cover motor cylinder 50 and in the opening of the curb cover element 34. In order to close the cover element 34, the air pressure in cover motor cylinder 50 is released by rotating the valve 63 back to its normal position in which the air conduit 62 is disconnected from the header branch 150a and is again vented through duct 144, T 146, duct 148 and solenoid valve GSV whose internal passage 154 is open to port 152 when the valve is deenergized.

It is desirable to be able to open and close the curb cover by hand independently of the power mechanism in case of an emergency or for any other purpose. To this end it will be observed that the power mechanism for returning and holding the cover element 34 in closed position is the yieldable tension spring 66. This spring is the only means resisting opening movement of the cover, since the air cylinder 50 is a one-way cylinder allowing free movement of its piston 52a in the direction of the cover opening movement of link 40. Accordingly, it will be seen that the cover element 34 may be swung open manually at any time by grasping and moving handle 156, whether during or out of the automatic cycle of the centrifugal machine.

In combination with the elements just described, Figure 5 also shows a loading control mech nism which prevents opening of the loading gate 20 until the cover element 34 has been opened. The mechanism, indicated generally at 158, comprises an air valve 160 having a valve body 162 formed with chambers 164 and 166 on opposite sides of a transverse partition 168, the chambers 164 and 166, respectively, having ports 170 and 172 for connection with air line 148 leading to the solenoid valve GSV and with air line 174 leading to the gate motor control device 260. The chambers 164 and 166 are-interconnected through partition 168 by an opening therein which is controlled by a valve element 176, the valve being biased to a closed, gate motor deenergizing position by a compression spring 178 acting upon one end of the element 176. The other end of the valve element 176 extends through the end wall of valve body 162 and is positioned to be engaged to be moved axially against the action of spring 178 to an open, gate motor energizing position by a lever arm 180 pivotally mounted :on an end wall of the valve body. The free end of the lever arm 18!) is positioned in the path of movement of an actuator arm 182 mounted on link 40 for movement 76 rate of closing movement ot the cover element 34, while The functions embodied in the loading control mechanism may be described as follows:

Actuation of solenoid valve GSV to its: energized po sition establishes a connection between duct 148 and header 150 and results in the admission of air under pressure into the cover operating motor cylinder 50 and at the same time in the admission of air into chamber 164 of the control valve 160. As long as the cover element 34 is in closed position, the valve element 176 remains in its gate motor deenergizing position under the action of spring 178 so as to prevent flow of pressure fluid to the gate motor control device 26a. However, when the cover element is moved to a predetermined open position, the actuator arm 182 swings lever arm 180 about its pivot in a direction to move the valve element 176 to its open, gate motor energizing position so as to allow fluid pressure to pass from chamber 164 to chamber 166 and thence to the gate motor control device 26a through duct 174.

It will be seen by the present arrangement, that energization of the gate motor 26 in the automatic cycle of operation is prevented when the curb opening 18 is covered by the cover element 34. However, it will also be seen that the curb cover element 34 can be moved freely to and from open position under the desired manual control of the centrifugal operator without interfering with the normal cyclical operation of the loading gate operating mechanism, for neither manual manipulation of the gate nor actuation of the valve 63 will result in the admission of fluid pressure into chamber 164 of the loading control mechanism 158. Accordingly, the valve element 176 may be moved to and from its open, gate motor energizing position with no effect on the operation of the gate motor 26.

The air flow through conduit 62 is retarded to a selected rate in each direction to give the desired rate of curb cover movement between its open and closed positions. For this purpose, air flow controls 122 and 124 are placed in series in conduit 62., Both air flow controls are identical in construction, which is shown in detail in Figure 6. As seen therein, control 122 is placed in normal position to restrict flow to the motor 50 to control the rate, of opening movement, and control 124 is in reversed position to restrict flow from the motor 50 to control the rate of closing movement. Each has a cylindrical body 126 formed with an axial bore 128 extending partially therethrough and open at one end of the body 126 for communicating with the conduit 62 and a laterally displaced axial bore 130 extending partially through the body open at the opposite end of body 126 for communicating with the conduit 62, the inner ends of the bores 128 and 136 being in overlapping relation and having a common wall 132 therebetween in which are disposed small orifices 134 and 136 that interconnect the bores 128 and 130 to complete the air passageway through the control. The effective size of orifice 136 in each flow control is regulated by an adjustable needle and the orifice 134 is controlled by a one-way ball valve 138 that permits flow therethrough in one direction and prevents flow therethrough in the opposite direction.

The valve 146 controlling the orifice 136 in flow control 122 is arranged to provide a controlled rate of flow of the compressed air passing through conduit 62 to the cover motor cylinder 58 so as to regulate the rate of opening movement of the cover element 34, and valve 138 controlling orifice 134 provides free by-pass around the needle valve 136 for back flow of compressedair passing through conduit 62 from the cover motor cylinder 50. Valves 140 and 138 in flow control 124 are in reverse arrangement to those in flow control 122 so that the rate of back flow of the compressed air passing through conduit 62 from the cover motor cylinder 50 is regulated by the needle valve 140 so as to control the 7 compressed air flowing to the motor cylinder 50 is: bypassed around needle valve 140' by theball valve 138.

The movable cover element 34" has an arcuate horizontal outline with a flat outer portion 72 that adapts itto-overlie the curb top 16 inclose relation thereto and a raised inner portion 74 that slopes upwardly and inwardly from the plane of the outer portion, having a relative level crest 76 formed with a peripheral recess 78 that, when the movable element 34 lies in closed position, forms with a corresponding recess 85) in a similarly raised portion $2 of the stationary element 32 a central aperture through which the spindle 14 extends. The aperture. so constituted by recesses 78 and 8b is formed to permit gyratory movement of the spindle. In the em bodiment illustrated, the back part of curb top is is provided with arecessed portion 84 (see Fig. 2) that extends rearwardly away from the spindle 14 to a location behind the loading gate 29 and opens forwardly into and forms a part of the curb top opening 13. The length of the recess icorresponds to the stroke of the movable cover element 34. The edges of the curb bordering recess' 8d form rearwardly extended side margins of the opening 18 which otherwise would be circular. By this construction the loading gate it) can be positioned directly over the rear portion curb top opening 18 formed by recess 84 with sufiicient clearance between the gate 20 and spindle 14 for the free and unobstructed how of charge material from the gate into the basket under the varying pressure head on such material in the supply tank.

The movable element 34 covers an arc of over 180, extending from alocation at the front and central part of the apparatus proximate the position indicated at A, which is normally occupied by the centrifugal attendant, around one side of the curb top 36 and terminating on the opposite side of the curb top at points beyond the vertical projection of loading gate 2d. The stationary element 32 covers an arc less than 180 and the two elements together, in the closed position of element 34, have margins which overlie the margins of Opening 18 and substantially cover the entire opening except at peripheral recessed portions 110 and 112 which serve to accommodate other units of apparatus associated with the curb top, such as, for example, the discharger, washing apparatus and control apparatus.

The back part of the cover element 34 extends into an integral trough portion 90 that is adapted to underlie the loading gate 20 in the closed position of the cover element 34 and catch material falling from the gate. The trough portion 9% projects rearwardly beyond the circular peripheral edge of the flat outer portion '72 and has edges which overlie the rearwardly' extended side margins of opening 18; The trough portion is constituted by a flat bottom Q8 at the level of the flat outer portion 72, two spaced upright side walls 92 and 9 that extend forwards and backwards of the loading gate 28, a fronttransverse wall 96 between the side walls that 'lies in front ofthe gate and slopes backwardly and downwardly from the crest portion 76 of the cover element 34 to the bottom 98, and a rear transverse wall 160 between the side walls that lies behind the gate and has afront portion Elm-sloping forwardly and downwardly to. the bottom 98.

At the-end of the trough 9i trailing the direction of curb movement, i. e. the left hand end as viewed in Eigures l and 2,. anoutlet is provided which opens into the. space between the basket. .12 and. the curb ii). .311% outlet 10%. is-constitutcdin part by a verticalopening formed partly inv the bottom 98 and partly in the sloping portion 102 of rear wall 100 and in part by a vertically cut away portion in the side wall 94 and adjacent said opening. The outlet serves to drain the material caught in the trough into a receiver 108 located below the; curb. top directly under the recessed portion 84: thereof. To facilitate the passing of material caught 3 by the trough. to. the outlet; 10.4, the inner surface 106- of the side wall 92 remote. from. the outlet and the bottom. 98 may also be sloped downwardly towardv said outlet.

In" the preferred form illustrated, the receiver 108 is an elongated. pan which is fixed. to the underside of the curb top 16 and extends to opposite ends of the recess 84 so that its opposite ends underlie the limit positions of the outlet 104. The pan is open upwardly and slopes downwardly and rearwardly from a closed front side lid, located in front of the forwardmost part of the path of movement of outlet M4, to an open back side 116 which is adapted to discharge material in the pan onto the inclined top wall 113 of basket 12. By this construction the pan underlies the outlet 1434 throughout its entire path of movement with the cover element 34 between open and closed positions of such element, and charge material falling from the trough through outlet 164 is deflected awayfrom the basket top opening 12%) and onto the outside surface of the top wall 118 of the basket. It will be evident that the windage caused by rotation of the basket within the curb 10 will elfect a sucking action that. will forcibly draw the drippings in the. trough into the space between the basket 12 and the curb lb. In this manner the drippings caught by the trough fill are continuously drawn ed and deposited into a collector outside the basket 12, thereby eliminating the usual drip pan scraping associated with known sugar centrifugals and maintaining the basket charge clean and free of drippings material that is commonly deposited into the basket and blemishes the charge and renders it nonuniform.

It will be understood that the foregoing detailedv description and the accompanying drawings are intended to exemplify the invention and that new parts, improvements and combinations herein disclosed may be em.- ployed in various other forms and arrangements of apparatus without departing from the substance of the dis closure or the intended scope of. the appended claims.

What is claimed is:

1. In centrifugal apparatus including a rotatable basket and a surrounding curb having an opening in its top wall permitting access to the basket, a unitary horizontally movable curb top cover, swingable link means holding said cover for movement between a normal closed position covering said opening and an open position exposing said opening, said link means including a pair of links, each of said links being'pivoted toa backward part of said cover and extending backwardly from it to a fixed pivot on a backward extension of said top wall, yieldable means connected to said link' means and acting continuously thereon to urge said cover to closed. position, power-operated means indriving relation to said cover for efiiecting movement of said cover to open position, said cover being movable toward open position independently of said power-operated means, andahandle on a part of said cover remote from said link means and by which said cover may at any time during or out of operation of said apparatus be moved manually to openposition against the force of said yieldable means.

2. In a cyclically operated centrifugal apparatus. in.- cluding a rotary basket, a curb surrounding the basket and having an opening in its top. wall permitting access to said basket, a loading gate for delivering chargematerial through said opening into the basket and poweroperated means for opening said gate, the combination comprising a curb cover movable from a normalclosed position covering said opening to an open positionexposing said opening, means rendered operative as said cover is moved to its closed position to render said gate opening means inoperable, and meansoperated' by' opening movement of said cover to render such gate opening means operable.

3*. In centrifugal apparatus includingia rotatable: basket,

a curb surrounding the basket and having an opening in its top wall permitting access to said basket, a loading gate for delivering charge material through said opening into the basket and fluid pressure operated means for opening said gate, a curb top cover movable from a normally closed position covering said opening to an pen position exposing said opening, fluid pressure operated means in driving relation to said cover for moving said cover to open position, each of said fluid pressure operated means having a supply line for leading fluid under pressure thereinto, control means for supplying fluid under pressure into said supply lines simultaneously to initiate a centrifugal loading operation, a valve in the fluid supply line of said gate opening means between the latter and said control means, means rendered opera-v tive by closing movement of said cover to hold said valve closed when said cover is in its closed position, and means operated as said cover opens to open said valve.

4. In centrifugal apparatus including a rotary basket, a curb surrounding the basket and having an opening in its top wall permitting access to said basket, a loading gate for delivering charge material through said opening into the basket and a gate operating motor, a curb top cover movable from a normal closed position covering said opening to an open position expo-sing said opening, a cover operating motor for moving the same to open position, gate motor energizin means including a shiftable element movable between a motor energizing position and a motor deenergizing position, a first energy supply line connected with said motor energizing means and comprising control means operable to supply energy to the latter, another energy supply line normally connecting said cover operating motor with said first line to supply energy to said cover operating motor upon operation of said control means, means rendered operative in response to movement of said cover to its closed position to hold said shiftable element in said motor decnergizing position, and means operated by opening movement of said cover to move said shiftable element to said motor energizing position.

5. In centrifugal apparatus including a rotatable basket, a stationary curb surrounding the basket and having ,a top opening permitting access to said basket and a loading gate located for delivery of charge material through said opening into the basket, a curb cover element movable horizontally from a normal closed position covering said opening to an open position exposing said opening, a portion of said cover element forming an upwardly facing trough below said gate to catch drippings from said loading gate, said trough underlying said gate when said cover is in its closed position and being displaced. from below said gate as said cover is moved to its open position, said trough being provided with an outlet for draining such drippings therefrom, and a fixed receiver extending horizontally below said outlet throughout the path of movement of said outlet to catch material draining from said trough in any position of said cover element.

6. In centrifugal apparatus including a rotatable basket, a stationary curb surrounding the basket and having a top opening permitting access to said basket and a loading gate located for delivery of charge material through said opening into the basket, a curb cover element movable horizontally from a normal closed position covering said opening to an open position exposing said opening, a portion of said cover element forming an upwardly facing trough below said gate to catch drippings from said loading gate, said trough underlying said gate when said cover is in its closed position and being displaced from below said gate as said cover is moved to its open position, said trough being provided with an outlet for draining such drippings therefrom, and a fixed receiver extending horizontally below said outlet throughout the path of movement of said outlet to catch material draining from said trough in any position of said cover element, said receiver comprising a pan mounted in the space between said curb top and the top of the basket and said curb top being cut away over said pan.

7. In centrifugal apparatus including a rotatable basket, a stationary curb surrounding the basket and having a top opening permitting access to said basket and a loading gate located for delivery of charge material through said opening into the basket, a curb cover movable horizontally from a normal closed position covering said pening to an open position exposing said opening, said cover being shaped to form spaced upright end walls to extend both forward and backward of said loading gate and spaced forwardly and backwardly sloping side walls extending between backward and forward ends, respectively, of said end walls, said walls defining an upwardly facing trough below said gate to catch drippings from said loading gate, said trough underlying said gate when said cOver is in its closed position and being displaced from below said gate as said cover is moved to its open position, said trough being provided with an outlet for draining such drippings therefrom and its bottom sloping toward said outlet,

8. in centrifugal apparatus including a rotatable basket, a stationary curb surrounding the basket and having a top opening permitting access to said basket and a loading gate located for delivery of charge material through said opening into the basket, a curb cover movable horizontally from a normal closed p sition covering said opening to an open position exposing said opening, a portion of said cover forming an upwardly facing trough to catch material falling from said loading gate, said trough underlying said gate when said cover is in its closed position and being displaced from below said gate as said cover is moved to its open position, and mounting means for said cover comprising a pair of links each having a relatively fixed pivot at one end, said fixed pivots being located on a backward extension of said curb cover, the other ends of said links being pivotally connected to said curb cover on opposite sides of said trough and in back of said gate, and the pivots of said links defining substantially a parallelogram.

References (fitted in the file of this patent UNITED STATES PATENTS 1,002,088 Smythe Aug. 29, 1911 1,921,446 Andrews et al. Aug. 8, 1933 2,142,209 Quinland Jan. 3, 1939 2,206,401 Hoffman July 2, 1940 2,254,388 Olcott Sept. 2, 1941 2,521,054 Ellis Sept. 5, 1950 2,638,225 Cox May 12, 1953 

